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1da177e4 LT |
1 | /* |
2 | * SoftDog 0.07: A Software Watchdog Device | |
3 | * | |
143a2e54 WVS |
4 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, |
5 | * All Rights Reserved. | |
1da177e4 LT |
6 | * |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | * | |
12 | * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide | |
13 | * warranty for any of this software. This material is provided | |
14 | * "AS-IS" and at no charge. | |
15 | * | |
16 | * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> | |
17 | * | |
18 | * Software only watchdog driver. Unlike its big brother the WDT501P | |
19 | * driver this won't always recover a failed machine. | |
20 | * | |
21 | * 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> : | |
22 | * Modularised. | |
23 | * Added soft_margin; use upon insmod to change the timer delay. | |
24 | * NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate | |
25 | * minors. | |
26 | * | |
27 | * 19980911 Alan Cox | |
28 | * Made SMP safe for 2.3.x | |
29 | * | |
30 | * 20011127 Joel Becker (jlbec@evilplan.org> | |
31 | * Added soft_noboot; Allows testing the softdog trigger without | |
32 | * requiring a recompile. | |
33 | * Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT. | |
34 | * | |
35 | * 20020530 Joel Becker <joel.becker@oracle.com> | |
143a2e54 | 36 | * Added Matt Domsch's nowayout module option. |
1da177e4 LT |
37 | */ |
38 | ||
27c766aa JP |
39 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
40 | ||
1da177e4 LT |
41 | #include <linux/module.h> |
42 | #include <linux/moduleparam.h> | |
1da177e4 LT |
43 | #include <linux/types.h> |
44 | #include <linux/timer.h> | |
45 | #include <linux/miscdevice.h> | |
46 | #include <linux/watchdog.h> | |
47 | #include <linux/fs.h> | |
48 | #include <linux/notifier.h> | |
49 | #include <linux/reboot.h> | |
50 | #include <linux/init.h> | |
4e57b681 | 51 | #include <linux/jiffies.h> |
f92d3749 | 52 | #include <linux/uaccess.h> |
7fff4beb | 53 | #include <linux/kernel.h> |
1da177e4 | 54 | |
1da177e4 LT |
55 | #define TIMER_MARGIN 60 /* Default is 60 seconds */ |
56 | static int soft_margin = TIMER_MARGIN; /* in seconds */ | |
57 | module_param(soft_margin, int, 0); | |
f92d3749 AC |
58 | MODULE_PARM_DESC(soft_margin, |
59 | "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" | |
60 | __MODULE_STRING(TIMER_MARGIN) ")"); | |
1da177e4 | 61 | |
4bfdf378 | 62 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 | 63 | module_param(nowayout, int, 0); |
f92d3749 AC |
64 | MODULE_PARM_DESC(nowayout, |
65 | "Watchdog cannot be stopped once started (default=" | |
66 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
1da177e4 LT |
67 | |
68 | #ifdef ONLY_TESTING | |
69 | static int soft_noboot = 1; | |
70 | #else | |
71 | static int soft_noboot = 0; | |
72 | #endif /* ONLY_TESTING */ | |
73 | ||
74 | module_param(soft_noboot, int, 0); | |
a77dba7e WVS |
75 | MODULE_PARM_DESC(soft_noboot, |
76 | "Softdog action, set to 1 to ignore reboots, 0 to reboot " | |
77 | "(default depends on ONLY_TESTING)"); | |
1da177e4 | 78 | |
7fff4beb AJ |
79 | static int soft_panic; |
80 | module_param(soft_panic, int, 0); | |
81 | MODULE_PARM_DESC(soft_panic, | |
82 | "Softdog action, set to 1 to panic, 0 to reboot (default=0)"); | |
83 | ||
1da177e4 LT |
84 | /* |
85 | * Our timer | |
86 | */ | |
87 | ||
88 | static void watchdog_fire(unsigned long); | |
89 | ||
90 | static struct timer_list watchdog_ticktock = | |
91 | TIMER_INITIALIZER(watchdog_fire, 0, 0); | |
1cc77248 | 92 | static unsigned long driver_open, orphan_timer; |
1da177e4 LT |
93 | static char expect_close; |
94 | ||
95 | ||
96 | /* | |
97 | * If the timer expires.. | |
98 | */ | |
99 | ||
100 | static void watchdog_fire(unsigned long data) | |
101 | { | |
1cc77248 CE |
102 | if (test_and_clear_bit(0, &orphan_timer)) |
103 | module_put(THIS_MODULE); | |
104 | ||
1da177e4 | 105 | if (soft_noboot) |
27c766aa | 106 | pr_crit("Triggered - Reboot ignored\n"); |
7fff4beb | 107 | else if (soft_panic) { |
27c766aa JP |
108 | pr_crit("Initiating panic\n"); |
109 | panic("Software Watchdog Timer expired"); | |
7fff4beb | 110 | } else { |
27c766aa | 111 | pr_crit("Initiating system reboot\n"); |
479d0f41 | 112 | emergency_restart(); |
27c766aa | 113 | pr_crit("Reboot didn't ?????\n"); |
1da177e4 LT |
114 | } |
115 | } | |
116 | ||
117 | /* | |
118 | * Softdog operations | |
119 | */ | |
120 | ||
121 | static int softdog_keepalive(void) | |
122 | { | |
123 | mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); | |
124 | return 0; | |
125 | } | |
126 | ||
127 | static int softdog_stop(void) | |
128 | { | |
129 | del_timer(&watchdog_ticktock); | |
130 | return 0; | |
131 | } | |
132 | ||
133 | static int softdog_set_heartbeat(int t) | |
134 | { | |
135 | if ((t < 0x0001) || (t > 0xFFFF)) | |
136 | return -EINVAL; | |
137 | ||
138 | soft_margin = t; | |
139 | return 0; | |
140 | } | |
141 | ||
142 | /* | |
143 | * /dev/watchdog handling | |
144 | */ | |
145 | ||
146 | static int softdog_open(struct inode *inode, struct file *file) | |
147 | { | |
1cc77248 | 148 | if (test_and_set_bit(0, &driver_open)) |
1da177e4 | 149 | return -EBUSY; |
1cc77248 | 150 | if (!test_and_clear_bit(0, &orphan_timer)) |
1da177e4 LT |
151 | __module_get(THIS_MODULE); |
152 | /* | |
153 | * Activate timer | |
154 | */ | |
155 | softdog_keepalive(); | |
156 | return nonseekable_open(inode, file); | |
157 | } | |
158 | ||
159 | static int softdog_release(struct inode *inode, struct file *file) | |
160 | { | |
161 | /* | |
162 | * Shut off the timer. | |
5f3b2756 | 163 | * Lock it in if it's a module and we set nowayout |
1da177e4 LT |
164 | */ |
165 | if (expect_close == 42) { | |
166 | softdog_stop(); | |
1cc77248 | 167 | module_put(THIS_MODULE); |
1da177e4 | 168 | } else { |
27c766aa | 169 | pr_crit("Unexpected close, not stopping watchdog!\n"); |
1cc77248 | 170 | set_bit(0, &orphan_timer); |
1da177e4 LT |
171 | softdog_keepalive(); |
172 | } | |
1cc77248 | 173 | clear_bit(0, &driver_open); |
1da177e4 LT |
174 | expect_close = 0; |
175 | return 0; | |
176 | } | |
177 | ||
f92d3749 AC |
178 | static ssize_t softdog_write(struct file *file, const char __user *data, |
179 | size_t len, loff_t *ppos) | |
1da177e4 LT |
180 | { |
181 | /* | |
182 | * Refresh the timer. | |
183 | */ | |
f92d3749 | 184 | if (len) { |
1da177e4 LT |
185 | if (!nowayout) { |
186 | size_t i; | |
187 | ||
188 | /* In case it was set long ago */ | |
189 | expect_close = 0; | |
190 | ||
191 | for (i = 0; i != len; i++) { | |
192 | char c; | |
193 | ||
194 | if (get_user(c, data + i)) | |
195 | return -EFAULT; | |
196 | if (c == 'V') | |
197 | expect_close = 42; | |
198 | } | |
199 | } | |
200 | softdog_keepalive(); | |
201 | } | |
202 | return len; | |
203 | } | |
204 | ||
f92d3749 AC |
205 | static long softdog_ioctl(struct file *file, unsigned int cmd, |
206 | unsigned long arg) | |
1da177e4 LT |
207 | { |
208 | void __user *argp = (void __user *)arg; | |
209 | int __user *p = argp; | |
210 | int new_margin; | |
f92d3749 | 211 | static const struct watchdog_info ident = { |
1da177e4 LT |
212 | .options = WDIOF_SETTIMEOUT | |
213 | WDIOF_KEEPALIVEPING | | |
214 | WDIOF_MAGICCLOSE, | |
215 | .firmware_version = 0, | |
216 | .identity = "Software Watchdog", | |
217 | }; | |
218 | switch (cmd) { | |
f92d3749 AC |
219 | case WDIOC_GETSUPPORT: |
220 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
221 | case WDIOC_GETSTATUS: | |
222 | case WDIOC_GETBOOTSTATUS: | |
223 | return put_user(0, p); | |
224 | case WDIOC_KEEPALIVE: | |
225 | softdog_keepalive(); | |
226 | return 0; | |
227 | case WDIOC_SETTIMEOUT: | |
228 | if (get_user(new_margin, p)) | |
229 | return -EFAULT; | |
230 | if (softdog_set_heartbeat(new_margin)) | |
231 | return -EINVAL; | |
232 | softdog_keepalive(); | |
233 | /* Fall */ | |
234 | case WDIOC_GETTIMEOUT: | |
235 | return put_user(soft_margin, p); | |
0c06090c WVS |
236 | default: |
237 | return -ENOTTY; | |
1da177e4 LT |
238 | } |
239 | } | |
240 | ||
241 | /* | |
242 | * Notifier for system down | |
243 | */ | |
244 | ||
245 | static int softdog_notify_sys(struct notifier_block *this, unsigned long code, | |
246 | void *unused) | |
247 | { | |
f92d3749 | 248 | if (code == SYS_DOWN || code == SYS_HALT) |
1da177e4 LT |
249 | /* Turn the WDT off */ |
250 | softdog_stop(); | |
1da177e4 LT |
251 | return NOTIFY_DONE; |
252 | } | |
253 | ||
254 | /* | |
255 | * Kernel Interfaces | |
256 | */ | |
257 | ||
62322d25 | 258 | static const struct file_operations softdog_fops = { |
1da177e4 LT |
259 | .owner = THIS_MODULE, |
260 | .llseek = no_llseek, | |
261 | .write = softdog_write, | |
f92d3749 | 262 | .unlocked_ioctl = softdog_ioctl, |
1da177e4 LT |
263 | .open = softdog_open, |
264 | .release = softdog_release, | |
265 | }; | |
266 | ||
267 | static struct miscdevice softdog_miscdev = { | |
268 | .minor = WATCHDOG_MINOR, | |
269 | .name = "watchdog", | |
270 | .fops = &softdog_fops, | |
271 | }; | |
272 | ||
273 | static struct notifier_block softdog_notifier = { | |
274 | .notifier_call = softdog_notify_sys, | |
275 | }; | |
276 | ||
1da177e4 LT |
277 | static int __init watchdog_init(void) |
278 | { | |
279 | int ret; | |
280 | ||
f92d3749 AC |
281 | /* Check that the soft_margin value is within it's range; |
282 | if not reset to the default */ | |
1da177e4 LT |
283 | if (softdog_set_heartbeat(soft_margin)) { |
284 | softdog_set_heartbeat(TIMER_MARGIN); | |
27c766aa | 285 | pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n", |
1da177e4 LT |
286 | TIMER_MARGIN); |
287 | } | |
288 | ||
289 | ret = register_reboot_notifier(&softdog_notifier); | |
290 | if (ret) { | |
27c766aa | 291 | pr_err("cannot register reboot notifier (err=%d)\n", ret); |
1da177e4 LT |
292 | return ret; |
293 | } | |
294 | ||
295 | ret = misc_register(&softdog_miscdev); | |
296 | if (ret) { | |
27c766aa JP |
297 | pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
298 | WATCHDOG_MINOR, ret); | |
1da177e4 LT |
299 | unregister_reboot_notifier(&softdog_notifier); |
300 | return ret; | |
301 | } | |
302 | ||
27c766aa JP |
303 | pr_info("Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout= %d)\n", |
304 | soft_noboot, soft_margin, soft_panic, nowayout); | |
1da177e4 LT |
305 | |
306 | return 0; | |
307 | } | |
308 | ||
309 | static void __exit watchdog_exit(void) | |
310 | { | |
311 | misc_deregister(&softdog_miscdev); | |
312 | unregister_reboot_notifier(&softdog_notifier); | |
313 | } | |
314 | ||
315 | module_init(watchdog_init); | |
316 | module_exit(watchdog_exit); | |
317 | ||
318 | MODULE_AUTHOR("Alan Cox"); | |
319 | MODULE_DESCRIPTION("Software Watchdog Device Driver"); | |
320 | MODULE_LICENSE("GPL"); | |
321 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |